In medical procedures such as laparoscopy, the patient's abdomen is distended to allow access to and visibility of the abdominal cavity. In order to distend the abdominal cavity, carbon dioxide gas is injected within the cavity. Gas insufflates the abdominal cavity, supporting the abdominal walls up and away from the internal organs. Without this pressure, the abdominal wall collapses and the visibility through a laparoscopic camera is lost.
While the abdomen is filled with gas, a trocar cannula (through which medical instruments can be inserted) transverses the abdominal wall. Valves are typically included in these cannulas to prevent gas from leaking from the pressurized cavity when the laparoscopic cannula is in use. Competence of these valves is desirable, in that even a small leak in the valve may cause a decrease in insufflation pressure and possibility of desufflation of the abdomen.
A variety of instruments are used with such cannulas. For example, forceps, clamps, scalpels, graspers, clip appliers, staplers, and dissectors are all known. These instruments typically have round cross sections and have outer diameters ranging from about 1 mm to about 30 mm. In many laparoscopic procedures it is necessary to remove a large diameter laparoscopic instrument and to replace it with a small laparoscopic instrument during the course of the procedure. In this event, it is not practical to replace the cannula at such times.
On the other hand, laparoscopic cannulas are available with lumen diameters of 5 mm, 7 mm, 10 mm, 12 mm, 18 mm, and 33 mm or other known sizes, with the larger sizes being preferred for laparoscopic procedures in which larger diameter laparoscopic instruments may be required. The valves used in such cannulas may be any valve which seals around medical instruments, such as those valves described in U.S. Ser. No. 899,397, filed Jun. 16, 1992, and incorporated herein by reference. However, all single valve systems may leak when small laparoscopic instruments are used in relatively large diameter trocar cannulas. A need has therefore existed for a universal cannula which may be adapted rapidly to accept instruments of varying sizes, and to provide a fluid tight seal around such instruments.
Some solutions have been offered. For instance, Stouder Jr., U.S. Pat. No. 5,211,633 discloses a surgical cannula with selectable seals which assure a fluid-tight fit around medical devices of a variety of sizes. The cannula includes a tubular member insertable into a patient and having a side wall defining a lumen through which a medical device may be inserted. The cannula also includes a housing mounted to a proximal end of the tubular member wherein the housing has a passage allowing insertion of a medical device therethrough and into the lumen. A movable member is mounted to the housing and is selectively movable between a first position and a second position across the passage. When the movable member is in its first position the passage accommodates insertion of a first medical device having a first outer cross-sectional dimension. A first valve body is mounted in the movable member and has a first opening therein corresponding in size to the outer cross-sectional dimension of a smaller second medical device, wherein the first opening is smaller than the passage. When the movable member is in its second position the first valve body provides a fluid tight seal around the second medical device.
In Ritchart et al., U.S. Pat. No. 5,209,737, a septum valve in a trocar assembly has a variable orifice that is responsive to a cross-sectional dimension of the surgical instrument being inserted into the trocar channel, thereby minimizing leakage of inflation gas from the body cavity, such as the abdomen, being operated on. An elastomeric septum is disposed in the channel and includes portions which define an orifice having in a relaxed state a first cross-sectional area. An actuation assembly provided with levers which pivot radially outwardly to expand the seal and thereby expand the orifice to the second cross-sectional area in response to entry of the instrument into the channel. The actuation assembly is free to float in an annular recess to accommodate an instrument which is misaligned with the trocar channel.
In Powers, U.S. Pat. No. 5,211,370, a variable orifice sealing valve is made from a thin, elastic cylinder. The cylinder is retained at both ends, and one end is twisted with respect to the other end thereby reducing the fluid flow path through the center of the cylinder. The device is particularly useful for medical procedures such as in conjunction with a catheter.
U.S. Pat. No. 5,197,955, incorporated herein by reference discloses a trocar assembly device that includes an improved seal assembly that accommodates instruments having a wide range of diameters. The seal assembly includes a universal seal member that is generally of hourglass shape defining converging and diverging side walls that form a constricted center bore portion therebetween. Various alternative means are provided to either increase or decrease the inner diameter of the center bore portion of the seal member.
Ser. No. 046,587, filed Apr. 12, 1993 (END-3) Stephens et al., incorporated herein by reference discloses an improved elastomeric seal member to maintain sealing engagement during off-centering or radial motion of instruments extending therethrough. The seal members include an inner section and an outer section. The inner section has an opening formed therein to permit an elongate instrument to pass therethrough in sealing engagement therewith. In accordance with certain embodiments, a corrugated portion is formed in the outer section. In accordance with certain embodiments an annular floating ring separates the inner section from the outer section.
Ser. No. 028,453, filed Mar. 9, 1993 and also incorporated herein by reference discloses an adaptor cap assembly is provided for a trocar, consisting of a base which contains an opening which is the same size as the opening of the trocar cannula handle. There is also a cap integrally attached to the base which contains a gasketing assembly wherein the assembly is of a smaller diameter than the diameter of the trocar cannula handle opening in the base of the adaptor cap assembly. This cap is hingedly attached to the base so that it can be flipped by using the thumb either into or out of alignment with the openings of the trocar cannula handle and the base of the adaptor cap assembly. Thus, this mechanism can be used so that a smaller diameter instrument can be placed within a larger diameter opening (with the adaptor cap in place), or, the adaptor cap can be moved out of place so that a larger diameter mechanism can be inserted within the adaptor cap assembly and into the trocar cannula handle, with both the base and the trocar cannula handle having the same size opening.
U.S. Pat. No. 5,104,383 to Schichman describes a valve wherein an adapter seal for use with a cannula assembly is provided. The adapter seal is provided with a stabilizer plate to limit the movement of an instrument relative to the seal.